Systems Analysis & Design: Topic 8
Finalization of the Analysis Phase
- studying the current system and defining the requirements
for a new system.
- the analyst uses fact-gathering techniques, such as
- reading existing documentation
- examining current procedures
- interviewing users and managers who deal with the system
- DFDs, data models, process descriptions, and a data dictionary
are used to describe both the current system and the requirements
of the new system.
- During this phase, analysts have their last chance to correct
errors and omissions easily and cheaply.
|Major Function:||To determine the requirements of a proposed new system.
|Principal Tools||fact-gathering techniques
|data flow diagrams|
|data models |
|Personnel and Tasks:||Users must continue to be heavily involved.
|1. The analyst studies and documents the current system in order to understand both its flaws and its strong points.
|2. The analyst prepares a list of requirements for a new system.
|3. The analyst diagrams the functions of the new system without specifying exactly how those functions are performed.
|4. The analyst may prepare a prototype of the system.
CHOOSING SOFTWARE AND HARDWARE
- At end of analysis phase the decision must be made as to whether
the computer software is to be built from scratch or purchased.
- Much of the design phase can be omitted if the decision is
made to purchase.
- Analyst evaluates available software packages to see if any
closely fit the users' needs.
- It is economically more feasible for many businesses, especially
smaller ones, to buy rather than to build software.
Advantages of commercial software
- Already debugged.
- Available sooner.
- Users can try out the product before investing a great deal
Disadvantages of a commercial software
- Only rarely will it precisely meet the needs of the users.
- It may not be compatible with existing software applications
in the organization.
- Different applications from different vendors mean that each
application will have a different user interface. With custom
programming, all of the user interfaces can be designed to be
- There may be no in-house expert on board since the programmers
and analysts may be no more familiar with the new software than
are the users.
- Commercial software packages often cannot be easily modified
if the needs of the users change in the future.
When evaluating commercial software consider the following:
- How closely does the package fit with what is needed? Will
it be necessary to modify the programs, or the proposed system
procedures, or both?
- How stable is the software vendor?
- Does the vendor give prompt, courteous, and reliable support
when problems arise?
- Will the vendor be providing ongoing enhancements and upgrades
to the software? At what cost?
- Are source programs supplied so that the organization can
do its own modifications?
- Is there a trial period during which the package can be returned
for a full refund?
- How many other installations have used the software package?
For how long? Who are they?
- How flexible is the software? Can it change along with the
changing business environment?
- Is the software user-friendly? Is the documentation clear,
complete, and easy to read?
- With what other applications currently used by your organization
does this application communicate?
- Only after collecting data on the various software packages
available does the analyst begin to worry about choosing the hardware.
- The software is really what determines how well the computer
system meets the user's needs.
Constraints on hardware selection
- stability of the vendor
- existence of a trial period
- satisfaction of other users
- machinery should be upwardly compatible
- Organizations must know comparative costs of the various system
solutions in both hardware and software selection.
- Cost-benefit analysis is performed at various stages of a
- First performed during the feasibility study to compare various
- Used at this stage
- to support the new system proposal, and/or
- to help choose between hardware/software alternatives
- When evaluating various alternatives both tangible and intangible
benefits and costs must be considered.
- Benefits alone have little meaning, but instead must be compared
to the associated cost and time estimates.
- Advantages measurable in dollars that accrue to the organization
through use of the information system.
- increase in speed of processing
- access to otherwise inaccessible information
- access to information on a more timely basis
- provision of new services
- Benefits that accrue to an organization from use of the information
system but which are difficult to assign a dollar value to.
- improved employee morale
- improved collection of accounts receivable
- fewer inventory shortages
- closer control and monitoring of investments
- Costs that require a cash outlay of the business. These costs
are typically well-established or can be found relatively easily.
- equipment costs
- costs of personnel time
- cost of resources
- operating costs (repair and maintenance, supplies, utilities)
- Costs that are difficult to estimate and may not be known.
- declining company image due to customer dissatisfaction
- ineffective decision making due to lack of timely information
- losing the competitive edge
Comparing Costs and Benefits
- Assess the economic feasibility of one or more options.
- Break-even Analysis -- examines the cost of the existing system
versus the cost of the proposed system.
- Payback Analysis -- determines the length of time it will
take before the new system is profitable, i.e., how long it will
take before the benefits of the new system offset the cost of
- Cash-flow Analysis -- examines the direction, size, and pattern
of cash flow that is associated with the proposed information
- Present Value Analysis -- takes into account the time value
of money by expressing all benefits and costs as their equivalents
in today's dollars.
How to Select Most Appropriate Technique:
- break-even analysis - used if the project needs to be justified
in terms of cost, not benefits, or if benefits do not substantially
improve with the proposed system.
- payback analysis - used when the improved tangible benefits
form a convincing argument for the proposed system.
- cash-flow analysis - used when the project is expensive, relative
to the size of the company, or when the business would be significantly
affected by a large drain on funds.
- net present value analysis - used when the payback period
is long or when the cost of borrowing money is high.